Physicochemical and nutraceutical properties of barley grass powder microencapsulated by spray drying

ABSTRACT

Barley grass (Triticum aestivum L.) is popular, commonly known as a nutritional supplement in China. To obtain the highest chlorophyll and flavonoid content as well as other physicochemical characteristics, spray drying from barley grass juice was carried out for two different maltodextrin concentrations (10 and 20%, dried basis) and four different inlet air temperatures (140, 150, 160, and 170°C). After drying, color, water activity, odor, taste, density, particle size, glass transition temperature, and chlorophyll and flavonoid contents of the dried product were measured. Highest contents of flavonoid (5.66 mg/kg) and chlorophyll (7.29 mg/kg) were obtained under 150°C inlet air temperature, 10% maltodextrin concentration, at a feed flow rate of 1.8 L/h for the drying. Corresponding particle size was 19.58–13.33 µm. The glass transition temperature (T_g) increased with the increasing of maltodextrin concentration; and two max T_g of powder obtained from 10 and 20% maltodextrin concentration were 74.4 and 77.4°C, respectively. Retention of taste and flavor were highest with 20% maltodextrin. High inlet air temperature was contributed to the large discrepancy of odor and taste substances. The best color (lightness L* = 64.44 and greenness b* = −11.53) was obtained at 150°C inlet air temperature and 10% maltodextrin concentration. Both maltodextrin concentrations resulted in poor flowability of the dried product (C_I ≤ 32.51).

KEYWORDS:

• Barley grass
• E-nose
• e-tone
• encapsulation
• powder
• vegetable pigment